Copy it into the scripts folder from GIMP, you will find it then under Filters -> Light and Shadow -> Rainy Landscape.
It doesn't have many options, because you can change them afterwards in the layers menu (ctrl-L).
I don't like the look of the existing beveling scripts so I wrote one up. It iterates shrinking selections to generate a bump map. It will use (in preferred order) the current selection, the alpha of the active layer, or the whole layer for the shape. The result is generated as a new layer set to hard light blend mode. It has:
- Inner and outer chisel/carve
- "Softness" parameter controls how hard/soft the heightmap bevel is
- "Effect Blur" parameter performs a post-bevel masked blur to make the chisel look more "puffy"
- Option to keep the bumpmap
Draws one of five types of predefined spirals, or lets the user modify the power parameter. The formula is:
r = a + b * theta ^ n
r - radius
a - growth factor
b - multiplication factor
theta - angle
n - power factor
The predefined types are: Archimedean (n = 1), Fermat (n = 1/2), Circle (n = 0), Lituus (n = -1/2), Hyperbolic (n = -1). If you choose a predefined type, the power factor you input on the form will be disregarded.